Grinding-disk for coffee-mills and the like.



H. L. JOHNSTON.

GRINDING DISK FOR GOFFEE MILLS AND THE LIKE. APPLIGATION FILED MAY 22, 1911.

1,089,41 3. Patented Mar. 1o, 1914 UNITED sTATEs PATENT oEEioE.

HERBERT Il. JOHNSTON, F TBOY, OHIO, ASSIGNOR TO THE HOBART ELECTRIC MANUFACTURING COMPANY, OF TROY, OHIO, A CORPORATION OF OHIO.

GnINDING-DISK non COFFEE-MILLS AND THE LIKE.

To all 'whom it may concern Be it known that I, HERBERT L. JOHNSTON, a citizen of the United States, and a resident of the city of Troy, in the county of Miami and State of Ohio, have invented certain new and useful Improvements in lGrrindin Disks for Coffee-Mills and the like, of whic the following is a full, clear, and exact description, reference being had to the accompanyingdrawing, forming a part of this specification.

The object of my invention is to provide a pair of coperating disks or burs for the grinding mills for cofee and the like, in which the teeth in each concentric row therefor are of 'uniform size, with the teeth gradually increasing in size for each radial row, whereby very effective grinding surfaces are provided, and at the same time the cost of manufacture is greatly chea ened, in that the teeth can be formed wit out the necessity ofv repeated adjustments necessary for vthe cutting of burs as ordinarily constructed.

In the drawing, Figure l isa plan view of the grinding disks, with one of the disks hroken away. Fig. 2 is a side elevation of the same. Fig. 3 is a cross section on the lines 3, 3, of lFig. 1. Fig. 4 is a plan view of one of the disks, illustrating the method of cutting the teeth.

l represents one of the disks, and 2 the companion disk, between which the material to he ground is passed. lhe two disks are provided with concentric rows of grinding teeth l3, 4, respectively, so that when the disks are placed together with the teeth intermeshing, the side faces of the teeth of one 'disk will form cuttin and grinding surfaces with the correspon ing teeth of the other disk. 'lhe construction and shape of the teethare determined by the method of cutting the same.

rIhe blanks upon which the teeth are to be cut are rst turned on a lathe, with a series of concentric V-shaped grooves 5, 5, as shown in Fig. 3. The blank is then secured on the dividin head of the. milling machine on an eccentric plate, so that the plate can be indexed on the center 6 of the blank, and so that the blank to be cutl can be swung on a center indicated at 7. The milling cutter is indicated at 8 in Fig. 4t, and this milling cutter rotates in xed position in the milling machine, while the work is swung in con- Specification o1' Letters Patent.

Application led Hay 22, 1911.

Patented Mar. 10, 1914i serial No. 628,789.

tact therewith on the center 7, and a transverseV-shaped groove is cut across the concentric V-grooves in the arc of a circle, of which the center is indicated at 7. When one of these transverse grooves is thus out, the disk 1s indexed for the next transverse cut on the center A6, and the cutting is prnceeded with until all of the transverse grooves are .formed for the entire circular ace of the disk. By thus cutting the teeth,

each tooth of any concentric row is of exactly the saine shape as all the other teeth 1n said row, and formed with an inclined V- shaped face 9 and an abrupt V-shaped face 10, with similar side faces l1 and 12. With this method gradually increase in size for each concentric row from the center outwardly. and when the two burs are placed together. the abrupt faces 10 ofthe teeth of the opposing burs give a shearing cut for the side faces of the teeth. Moreover, as the material to he ground is introduced at the center, and is forced outwardly, the smaller teeth which do not interlock fully, first attack the material and the curvature of the transverse grooves follows more nearly the natural path of the flow of the grain. The teeth of each concentric row are all of exactly the same size, and a more uniform grade of inding is the result. The cost of manuacture of the greatly cheapened. The disk is secured in fixed position for indexing on the center 6 and thereafter the disk itself does not have to be released until all the transverse grooves are cut and the cutting of the teeth is com pleted. Each tooth is accurately cut, and the teeth of the two cooperating disks, when placed together, fit together accurately to form the required cutting and grinding surfaces when the one disk is rotated on the other.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is:--

l. A pair of cooperating disks for codec mills and the like, provided with concentric rows of uniformly pyramidal teeth, the teeth of each concentric row being of uniform size and gradually and uniformly increasing in size for ,each radial row for both disks from the center to the periphery, with the radial faces of the teeth cut on the same arc of a circle eccentric of the center of the disk of cutting the teeth, the teeth grinding disks is also very each` disk, the center of the cutting arc4 being uniformly advanced around the peri hery 15 of the disk for the radial rows of both gisks, each tooth for each concentric row havin' an abrupt and an inclined V-shaped radia face, wlth similarly inclined side faces, whereby when the twi; disks are placed to- 20 gether the abrupt radial faces of the teeth will give a shearin cut with the side faces.

HERBERT L. JOHNSTON.

Attest:

E. E. EDGAR, R. W. DEWEESE. 

